Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA.
Molecules. 2019 Jan 9;24(2):227. doi: 10.3390/molecules24020227.
Previous work has demonstrated that a bidentate receptor containing a pair of Sn atoms can engage in very strong interactions with halide ions via tetrel bonds. The question that is addressed here concerns the possibility that a receptor of this type might be designed that would preferentially bind a polyatomic over a monatomic anion since the former might better span the distance between the two Sn atoms. The binding of Cl was thus compared to that of HCOO, HSO₄, and H₂PO₄ with a wide variety of bidentate receptors. A pair of SnFH₂ groups, as strong tetrel-binding agents, were first added to a phenyl ring in ortho, meta, and para arrangements. These same groups were also added in 1,3 and 1,4 positions of an aliphatic cyclohexyl ring. The tetrel-bonding groups were placed at the termini of (-C≡C-) ( = 1,2) extending arms so as to further separate the two Sn atoms. Finally, the Sn atoms were incorporated directly into an eight-membered ring, rather than as appendages. The ordering of the binding energetics follows the HCO₂ > Cl > H₂PO₄ > HSO₄ general pattern, with some variations in selected systems. The tetrel bonding is strong enough that in most cases, it engenders internal deformations within the receptors that allow them to engage in bidentate bonding, even for the monatomic chloride, which mutes any effects of a long Sn···Sn distance within the receptor.
先前的工作已经证明，含有一对 Sn 原子的双齿受体可以通过四键与卤素离子发生非常强的相互作用。这里要讨论的问题是，是否有可能设计出这样一种受体，它会优先与多原子阴离子结合，而不是单原子阴离子，因为前者可能更好地跨越两个 Sn 原子之间的距离。因此，与 Cl 相比，对各种双齿受体的结合情况进行了比较。一对 SnFH₂ 基团作为强四键结合剂，首先被添加到邻、间和对位的苯环中。这些基团也被添加到脂肪族环己基的 1,3 和 1,4 位置。四键结合基团被放置在（-C≡C-）（= 1,2）延伸臂的末端，以进一步分离两个 Sn 原子。最后，Sn 原子直接被整合到一个八元环中，而不是作为附加物。结合能的排序遵循 HCO₂>Cl>H₂PO₄>HSO₄ 的一般模式，但在某些选定的系统中存在一些变化。四键键合足够强，以至于在大多数情况下，它会使受体发生内部变形，从而使它们能够进行双齿键合，即使对于单原子氯也是如此，它抑制了受体内部 Sn···Sn 距离的任何影响。
